Portable safety lamp



Oct. 4, 1960 w, H. GUILD 2,955,195

PORTABLE SAFETY LAMP Filed Aug. 28, 1958 2,955,195 PORTABLE SAFETY William H. Guild, Hingham, Mass., assignorto Carpenter lcuhfg. Co., Somerville, Mass., a corporation of Massausetts I 4 Filed Aug. 28, 1958, Ser. No. 757,86 8

l'Claim. c1. 240-113 This invention relates to portable lamps foruse in potentially explosive atmospheres and more particularly it is concerned with, an automatic quenching device for such lamps whereby the filament of a broken lamp bulb is automatically cooled.

In locations where the danger of an explosion exists due to the presence of explosive gases in; the surrounding atmosphere, such as in a mine, precautions must be taken to prevent the atmosphere from reaching an element that is sufliciently hot that it might ignite the gases. The filament of an incandescent lamp bulb is such an element.

2,955,195 'Patented Oct. 4, 1 9 60 ward portion of the housing and a lens extends across the forward end thereof through which light is to pass. The reflector 14 and the lens 15 are both clamped to the rim of the housing with a gasket 16 between them, the

clamping of these parts bieng effected by a circumferential ring 17.

At the center of the reflector 14 there is an aperture and in the region of the aperture there is affixed to the reflector a lamp socket 18. The socket 18 carries a helical compression spring 19 whereby the bulb 21 disposed in the socket is urged forwardly or towards the right of Fig. 1. Acting to move the bulb in the opposite direction,

that is towards the left, is a cup-shaped quenching element 22 which overlies a portion of the bulb-at its forward end. The action of the quenching element on the bulb is created by a tension spring 23 which is connected to the quench- Accordingly, there have been developed for use in mines,

and other locations where explosive gases are likely to exist, portable lamps that incorporate quenching elements for the filaments of the lamp bulb. Such a quenching element does not act on the lamp bulb filament of a lamp when it is operating normally and the filament is insulated from the surrounding atmosphere by the glass shell of the bulb as well as the lamp housing. Rather, it isjwhenthe glass shell of'the bulb is accidentally brokenthat the quenching element is adapted to move into contact with the filament so as to cool it. Of course, the movements of the quenching element must be rapid so that it comes in contact with the filament before it is exposed appreciably to the atmosphere, and the mass of the quenching element must be sufiicient to cool down the filament rapidly. Heretofore relatively complicated mechanisms have been required to realize these objectives.

It is an object of the present invention to provide a portable lamp incorporating a quenching device that is relatively simple to manufacture and has a minimum of constituent parts.

It is a further object of the invention to provide in combination with the quenching device a mechanism for breaking the energizing circuit for the lamp bulb when it is accidentally broken.

The novel features of the invention together with further objects and advantages thereof will become apparent from the following detailed description and the drawing to which it refers.

In the drawing:

Fig. 1 is a sectional view of a portable lamp according to the invention with the parts in normal operating position;

Fig. 2 is a sectional view similar to Fig. 1 illustrating the position of the parts when the lamp bulb has been broken; and

Fig. 3 is an exploded view in section of the base of the lamp bulb and the socket therefor.

With reference now to the drawing, and more particularly to Fig. 1, it will be observed that thelamp comprises a housing 11 having a concave forward portion 12 and an elongated rearward portion 13 extending axially therefrom. The forward portion is shaped in the manner of a hemispherical shell which defines a light-radiating aperture, and the rearward portion is generally cylindrical in shape thereby to provide a convenient means for carrying the lamp. A reflector -14 is-disposed within the for ing element by means of a yoke. The yoke is seen to include a crosspiece 24 and a pair of arms formed from a length of wire 25 having its ends hooked through the crosspiece. As shown, the wire is twisted together at the base of the quenching element and beyond the twist there is a loop 25'. Silver soldering is a convenient way of attaching the quenching element to the wire. The spring 23 is at one end hooked to the crosspiece 24 and at the other end connected to the back of the housing. The latter connection is made with a screw 26 which projects through the housing and is provided with a cross-bore through which the spring is hooked. A cap nut on the exposed end of the screw holds it in place, and bymeans of the cap nut the tension of the spring 23 can be precisely adjusted.

The socket 18 is shown more in detail in Fig.3. It comprises a cylindrical body 3 1 of insulating material and a conductive outer shell 32 which surrou nds approximately the forward half of the body and extends approximately an equal distance therebeyond. The shell is staked to the body. There are two parallel spaced bores extending lengthwise of the body which carry a pair of contacts 33 and 34. The contacts are bored for a distance from the back of the socket so that wires can be readily connected to them. The wires are held in place by set screws 35 and 36 threaded into the body and the contacts themselves are locked in place by means of pins 37 and 38. There are slots 39 in the shell which cooperate with pins 41 on the base of the lamp bulb to fix the angular position of the bulb contacts with respect to the contacts 33, 34 in the socket. A salient feature of this socket construction is that there is no spring loading of the socket contacts as is conventional. Rather, the positions of the contacts with respect to the shell and body of the socket 18 are fixed by the pins 37 and 38 and hence the contacts cannot move forwardly when the bulb does.

The reason that the bulb has two contacts in addition to its base shell, which serves as a common or ground contact, is that the bulb has two filaments. The filaments are adapted to be selectively energized by means of a switch 41 attached to the housing as shown in Fig. 1. Switch 41 is of the single-pole double-throw type and has, in addition to a pair of circuit-making positions, a neutral position in which its movable contact 42 is disconnected from its stationary contacts 43 and 44. Contact 42 and the shell 32 of the socket are connected to a source of power (not shown) by means of wires 45 and 46. Contacts 43 and 44 are connected to the contacts 33 and 34 of the socket by means of wires 47 and 48. With this arrangement the bulb can be used for a longer time before it needs to be replaced since only one filament is used at a time, and after it burns out the other can then be used.

A convenient source of power for the lamp is a battery. Neither the battery nor the usual carrying case therefor have been shown because they may be entirely conventional and are unrelated to the basic structure according to the invention. It is contemplated, however, and indeed preferred, that a suitable battery and battery case be probecause theyarefixcd. Therefore,-thecircuit1othe,bnlb

is immediately broken, and the bulb starts .to cool even before the bulb filament makes .contact .with thequenching element as shownin Fig.- 2. Contact between .thequenching element and the filament is established very rapidly since 'both springs act tobring .them together, and:ther.eby

acceleratelthe cooling ofihe filament. ,Spring 23 does ,not continue .to act, however, because ,it ,is in .a contracted state in Fig. 2. Rather, spring .19 maintains the broken bulb in the open .circuitposition of Fig. 2 so that it .can be replaced Whenever convenient. To this end .loop 15 provides a finger-hold wherebythe quenching element .can be drawn forwardly out of ttheway of the broken :bulb.

Although the invention has been-described in connection witha single preferred embodiment, .it will be-appreciated that this-embodiment canbemodified in numerture and an axially extending rearward portion having a reduced diameter adapted to serve as a carrying handle, a reflector disposed within the forward portion of said housing, an incandescent lamp bulb, a socket for the bulb provided with contacts fixed therein adapted to be electrically connected to a circuit for energizing the lamp and with guide means to locate angularly the position of the bulb with respect to said contacts, said socket being rigidly mounted withits forward end .at -:the center of said refiector and said reflector being centrally apertured to receive the socket, -a compression spring retained in said socket to-urge saidbulb forwardly out of registry with said contacts, a tension spring extending axially within the rearward reduced diameter :portion of said housing with one of its ends aflixed thereto, a cup-shaped quenching element overlying an exposed forward end portion of said bulb, a yoke including a crosspiece for connection to the other end of said tension spring and a pair of arms projecting through vsaidgnefleetor ,for'lconnection' to ,said quenching element, and .rneans tor adju ting the tension of said tension spring, :said arms being formed with a length .of wire that ,is hooked :to .said erosspiece at both ends and extends on each side of said socketand the bulb and is .twistedtogether at a point ,remotefrom said crosspieceto provide aseradlefor said quenching element and a finger loop whereby the .guenching element can be drawn out @of the way ,of said bulb, said quenching ,element acting to urge-the bulb ,rearwardly intoregistry with said contacts :and .when :the bulb .is broken to. contact the filament :thereof.

- References Cited inlhe file ,oflthis patent PATENTS 

